This invention relates generally to weight distributing hitches of the type that are commonly used to couple a towed vehicle, such as a travel trailer, to an automotive towing vehicle, such as an automobile, truck, or van. More specifically, the invention relates to a new and improved lift unit for such a weight distributing hitch.
When a automotive vehicle is used to tow a trailer, an articulated joint coupling between the two is a virtual necessity. For a trailer that has a comparatively small tongue weight, a simple ball joint coupling is usually all that is necessary because the attachment of the trailer to the automotive vehicle will not concentrate an excessive downward force at the rear of the towing vehicle. However, for larger tongue weights, it is preferable to use a weight distributing hitch which can transfer the tongue weight to the towing vehicle in a manner which disributes the weight more forwardly on the towing vehicle.
Various embodiments of weight distributing hitches have been proposed over the years, and a number of them have enjoyed significant commercial usage. Examples are shown in various expired U.S. patents to Reese and Mathisen. While these weight distributing hitches contain a ball joint coupling that provides the basic articulation, they also include a weight-distributing platform that attaches to the towing vehicle and spring bars that are disposed to each side of the ball joint coupling and flexed between the towing and towed vehicles in a manner that transfers a portion of the tongue weight directly to the weight distributing platform so that the full tongue weight is not imposed on the ball joint coupling.
A representative spring bar has its forward end removably fitted in a pivot joint connection disposed to the side of the ball so that the spring bar can swing generally horizontally to follow articulation of the ball joint coupling whenever the towing vehicle makes a turn. The spring bar extends generally rearwardly in an underlying relationship to one side of the trailer tongue. Flexing of the spring bar is accomplished by elevating its rearward end upwardly toward the tongue through the use of a lift bracket that is mounted on the tongue's side a certain distance rearwardly of the ball joint coupling. A length of chain is commonly used to transmit the motion of the lift unit to the spring bar.
In one type of weight distributing hitch the spring bars are connected directly to their lift units so that operation of the lift units to elevate the chains pulls directly on the rearward ends of the spring bars. In another type of weight distributing hitch, the lower end of the chain is attached to the trailing end of a lever whose forward end is pivoted about a generally horizontal axis at a location on the side of the tongue that is between the ball joint coupling and the lift unit. The rear of spring bar is supported by the rear of this lever so that when the rear of the lever is elevated by the chain, the rear of the lever will lift the rear of the spring bar along with it thereby flexing the spring bar.
Various embodiments of lift units are illustrated in prior patents. One type of lift unit comprises a bracket portion that mounts on the trailer tongue and provides a generally horizontal hinge axis for a hinge portion of the lift unit. This hinge portion of the lift unit contains a suitable means for connection of the chain, such as a hook onto which a link of the chain can be inserted, and a suitable means for engagement by a removable tool that is used as a lever to rotate the hinge portion about the hinge axis for raising and lowering the chain. Typically, the hinge portion is constructed and arranged in relation to the line of action of the force that is applied through the chain so that as the chain is elevated over a final increment of travel to raised position, the hinge portion goes slightly over center and is stopped by abutment with the bracket portion. In this way, the force of the flexed spring bar that is transmitted through the chain to the hinge portion of the lift unit will tend to keep the hinge portion in its stopped abutment with the bracket portion. In general, it is desirable to provide a means for releasably locking the hinge portion in this over center position and removable locking pins, or the like, are typically employed for this purpose. Accordingly, such a lift unit will have suitable holes in its bracket and hinge portions which align with each other when the hinge portion is brought to the over center position. The pin is passed through the aligned holes to thereby constrain the hinge portion against rotation on the bracket portion. These pins are suitably shaped to provide for convenient attachment and removal without the use of separate tools, and yet are designed to remain in place during typical over-the-road travel that will be encountered when the trailer is towed by the automotive vehicle.
The present invention relates to a new and improved mechanism for automatically locking the hinge portion of the lift unit to the bracket portion of lift unit as the hinge portion is swung to a position that completes the elevation of the chain. The disclosed embodiment comprises a locking member mounted on the hinge portion that operates by force of gravity to engage a catch in the bracket portion to perform the locking function. When it is desired to lower the chain, the locking member is manually disengaged from the catch, enabling the hinge portion to be operated to lower the chain. Moreover, operation of the hinge portion to full chain lowering position brings the hinge portion to a condition where the locking member automatically resets itself so that subsequent operation of the hinge portion to elevate the chain will again cause the locking member to automatically lock the hinge portion to the bracket portion as the hinge portion once again comes to the full chain elevating position.
In order to assure that accidental disengagement of the locking element from the catch will not occur when the hinge portion is locked in the full chain elevating position, both the locking member and the hinge portion are provided with holes that align with each other when the hinge portion is in full chain elevating position and the locking member is engaged with the catch. A tethered pin is removably inserted through these aligned holes to prevent the locking member from being disengaged from the catch. Removal of the pin enables the locking member to be disengaged from the catch for subsequent lowering of the chain in the aforementioned manner.
The automatic locking feature of the present invention is embodied with comparatively few and simple parts. The catch is incorporated as a notch into the design of the bracket portion. The locking member is a flat metal part that is connected by a pivot pin to the side of the hinge portion
The foregoing features, advantages and benefits of the invention, along with the additional ones, will be seen in the ensuing description and claims which should be considered in conjunction with the accompanying drawings. The drawings disclose a presently preferred embodiment of the invention in exemplary usage, according to the best mode contemplated at the present time in carrying out the invention.